Fire behavior and mechanical properties of phosphorus-containing silica gel coated ammonium polyphosphate as fire retardants in thermoplastic polyurethane (TPU)

Abstract

To enhance its properties, ammonium polyphosphate (APP) was subjected to modi cation using a synthesized phosphorus-containing silica gel, resulting in MAPP. Ammonium polyphosphate (APP) was modi ed by synthesized phosphorus-containing silica gel, resulting in MAPP, which was then used to form thermoplastic polyurethane composites. MAPP exhibited better thermal stability with a smaller dispersion size, lower initial decomposition temperature and better resistance to heat at high temperatures than APP. At the same time, MAPP showed more obvious advantages in improving the char yield, ame retardant performance and mechanical properties of TPU. TPU/5%MAPP showed a limiting oxygen index of 29.1% during burning tests, signi cantly better than TPU/5%APP (27.3%). The cone calorimeter test results also indicated that the incorporation of MAPP resulted in a signi cant reduction in key parameters such as peak heat release rate, total heat release, and total smoke release and an increase of the char yield of TPU composite. The TG result showed that the T max of the TPU/5%MAPP composite increased and the mass loss rate decreased compared with that of TPU/5%APP. Moreover, the tensile strength of the TPU/5%MAPP composite increased by 18.5% compared with the TPU/5%APP composite due to the improved dispersibility of MAPP than APP. An analysis of the re resistance mechanism showed that the improved ame retardance in the TPU/5%MAPP composite resulted from the structural changes in the char residue. This study provides an e cient and extensible approach for the synthesis of high-performance ame retardant TPU materials. Highlight 1. MAPP was prepared by modifying APP with phosphorus-containing silica gel.2. MAPP has good compatibility with TPU and can be uniformly dispersed in TPU.3. MAPP endows TPU with excellent ame retardancy and mechanical property. 4. Compared with TPU, the pk-HRR and TSR of TPU/5%MAPP decreased by 68.6% and 43.8%. 5. The tensile strength and the elongation at break of TPU/5%MAPP is 32 MPa and 618%.

Characterization and Flame-Retardant Properties of Cobalt-Coordinated Cyclic Phosphonitrile in Thermoplastic Polyurethane Composites

“…However, TPU is an extremely flammable material, The molten droplets generated during the combustion process not only spread the fire but also release a significant amount of toxic and harmful gases, such as CO, HCN, NOx, etc. This poses a serious limitation on the application of TPU [7][8][9]. Inorganic flame retardants are commonly utilized in polymer for their non-flammable nature and high specific heat capacity, but their compatibility with TPU materials is lacking, necessitating the addition of large quantities, ultimately leading to a reduction in the mechanical properties of the polymer [10,11].…”